Separation of cyclopentanone



Dec. 23, 1952 Q ,y ct. RAY SEPARATION oF CYCLOPENTANQN'E Filed sept. 2v, 194e Patented Dec. 23, 1952 SEPARATION OF CYCLOPENTANONE Gardner C. Ray, Bartlesville, Okla., assig'nor to Phillips Petroleum Company, a corporation of Delaware Application September 27, 1946, Serial No. 699,665

2 Claims.

This invention relates to a distillation process. In one aspect this invention relates to the separation of a cycloalkanol, such as cyclopentanol, and/or a cycloalkanone, such as cyclopentanone, from water. In still another aspect this inventlon'relates to a process for the manufacture of an oxygenated cycloalkyl.

Cyclopentanol and cyclopentanone are highly valuable organic compounds used as explosives intermediates, solvents, organic synthesis intermediates, etc. Commercial processes involving their production and purification are, therefore, desirable. In the course of the production or utilization of these compounds, they are often obtained admixed with appreciable quantities of water, and in some cases, water-soluble, nonvolatile acids or alkalis are also present.

An object of this invention is to provide a continuous process for the recovery of cyclopentanol and/ or cyclopentanone from their aqueous solutions.

Another object of this invention is to provide a method for separating the components of a mixture comprising cyclopentanol, cyclopentanone and water.

Still another Aobject of this invention is to provide a process for the manufacture and purincation of cyclopentanone.

A further object of this invention is to provide a process for the manufacture and purication of cyclopentanol.

A still further object is to provide a process for the removal of water from a solution of an oxygenated cycloalkyl.

Other objects and advantages will become apparent from the accompanying description and disclosure.

The drawing represents a diagrammatic showing of apparatus adapted to carry out the invention.

In. ordinary distillation at atmospheric pressure, cyclopentanone and cyclopentanol have normal boiling points of about 130 C. and about 140 C., respectively. Since water has a normal distil simultaneously at 92.6 C. at a pressurel of 740 mm. of mercury to produce a distillate having a composition of about 64 volumeper cent TABLE I Cyclopenta- Water in cy- Cyclopentanol Water in cynone in water, clopentanone, in water, vol. clopentauol, vol. percent vol. percent percent v01. percent Upon cooling and condensing either the cyclopentanone-water azeotrope or the cyclopentanolwater azeotrope from their normal boiling ternperatures to F., two liquid phases result, a Water-rich phase and an organic compound-rich phase. A considerable concentration of cyclopentanone or cyclopentanol results from the azeotropic distillation of somewhat dilute aqueous solutions of either the ketone or the alcohol. If desired, the upper or organic phase of the condensed azeotropic distillates may be redistilled to produce a quantity of anhydrous ketone or alcohol since insuicient water is present in these phases to form an azeotropic mixture with all the ketone or alcohol present. l

If quantities of non-volatile acids or bases, such as sulfuric acid or sodium hydroxide, are present, it is sometimes advantageous to introduce additional water into the aqueous mixtures containing cyclopentanol or cyclopentanone prior to azeotropic distillation. Reducing the concentration of the acid or base present in this manner oftentimes eliminates the occurrence of undesirable side reactions, such as the dehydration of the alcohol, polymerization of the ketone, esterilcation of the alcohol, and the like.

In view of the above discoveries, a solution of water and a cycloalkanol and/or a cycloalkanone,

the alcohol and the ketone possessing partial solubility with water and preferably containing a single ring having not more than six` carbon atoms permolecu1e, is separated into its components by a series of continuous azeotropic distillation steps. Since two liquid solutions of 2 to 3 hours.

tropic mixture of water and the organic comi pound is removed therefrom as an overhead product. The overhead product is condensed and allowed to separate into 'two liquid phases, a solvent-rich phase and a solute-rich phase. The solvent-rich phase is returned to the first distillation zone and the solute-rich phase is introduced into a second distillation zone and a bottom product comprising the solute and an overhead product comprising substantially an azeotropic mixture of water and the organic compoundl are removed therefrom. This overhead fraction from the second distillation zone is also condensed and separated into two liquid phases in the same step as the overhead from the rst distillation zone. If either the solute or the solvent Withdrawn as a bottom product comprises a mixture ofv a ketone and an alcohol,

this mixture may be separated into its components in a third distillation step.

The above data for the phase relationships and the properties of the mixture of water, alcohol and ketone will vary somewhat with pressure and alterations or changes in pressure to gain similar results is within the scope of this invention.

As an example of the application of the knowledge imparted by this invention, a process for the production and purification of cyclopentanol and cyclopentanone will be described with reference to the drawing accompanying this application. Although the azeotropic properties of cyclopentanol and cyclopentanone with water are especially applicable to the processes to be described, the accompanying description should not be construed to limit the applica-tion of this invention to such a process, According to the drawing, Cyclopentene and sulfuric acid together with water are introduced into hydration reactor 'l through lines 6 and respectively. The cyclopentene feed may be obtained from various sources, such as petroleum refinery processes. When using about 65 to about 75 per cent sulfuric acid, appropriate reaction conditions for effecting the hydration of the Cyclopentene are a temperature of about 75 to about 85 F. at atmospheric pressure and a residence time of about With such conditions the conversion of Cyclopentene to cyclopentanol is about 50 to about 80 per centper pass. A liquid eluent from reactor 'l is passed therefrom through line 8 and admixed with water entering line 8 through line 9. Water-is added to the eilluent in order to hydrolyze the sulfuric acid esters and to sufficiently dilute the acid to prevent or minimize side reactions (asalcohol dehydration) during subsequent distillation steps. The resulting aqueous mixture is cooled (not shown) and vis then passed to separator Il wherein a liquid organic phase and liquid aqueous phase ar-e formed. The lighter organic phase comprising polymers and unreacted hydrocarbons, and other side reaction products is removed from separator l-I through line l2 and discarded, if desired. or distilled to recover cyclopentanol if an appreciable quantity is present. The aqueous phase which contains sulfuric acid and cyclopentanol and which has been diluted to about a 5 to l0 per cent concentration of acid is passed through line lil to distillation zone I6. Water and sulfuric acid substantially free from cyclopentanol are withdrawn from disitllation zone I6 as a bottom product through line Il and water and cyclopentanol are withdrawn as an overhead product through line The aqueous sulfuric acid withdrawn from column lil through line il may be reconcentrated by distillation and returned to reactor l for reuse in promoting the hydration reaction. previously stated, the overhead azeotropic mixture has acomposition of about 43 volume per cent cyclopentanol and about 57 volume per cent water. The overhead fraction is condensed and separated into two liquid phases by passing the stream through condenser I9, line 2l into accumulator 22. The upper cyclopentanol-rich phase containing about 16.8 volume per cent water is passed to a second distillation zone 25 through line 26 for further fractionation. The

.lower aqueous phase in settler 22 .containing about 9.6 volume per cent cyclopentanol is returned to column I6 through line 23, preferably to the feed plate of that column.

In distillation column 26 a second separation is made between cyclopentanol and water; and azeotropic mixture of cyclopentanol and water is withdrawn overhead from column 26 through line 2l andrecycled through condenser i9 to separator 22. '.This azoetropic mixture is similar in composition/to theazeotropic overhead mixture 0i column I6 and therefore can be separated inte two phases in a similar manner as the overhead in column i6. Since insufcient water is present in the feed to column 25 to form an a'zeotrcpic mixture with all the cyclopentanol present. cyclopentanol substantially free from water is withdrawn as a liquid from column 26 through lines 28 and 52 as a product of the process. The approximate boiling point of the cyclopentanolwater azeotrope is about 96 C. while the boiling point of cyclopentanol itself is about C.; thus it is apparent that the separation between the cyclopentanol and the azeotrope may be eifected with ease in column 26.

When cyclopentanol is not the desired product but is an intermediate product in the production 0f cyclopentanone, cyclopentanol is passed through line 28 to reactor 29 in which the cyclopentanol is converted to cyclopentanone. The conversion of cyclopentanol to cyclopentanone is effected inthe presence of a catalyst, such as nickel or brass. Since the conversion products, aside from cyclopentanone, are somewhat different depending upon the catalyst, the purification of the conversion effluent must be eifected accordingly. When nickel is used as the catalyst,

.the conversion is carried out at a temperature of about 260 C, at about atmospheric pressure. The normally liquid portion of the conversion eiluent under certain conditions comprises approximately the composition shown in Table 'II below.

TABLE I1 Component: Volume percent Cyclopentene 5 Cyclopentano1 V 20 Cyclopentanone 20 Water APolymers 5 The conversion effluent from reactor 29 is passed `v'therefrom through line 30 to a gas separator 3| in which hydrogen is separated from the liquid eluent. From gas separator 3l the liquid conversion eilluent is passed to a first distillation zone 32. In distillation zone 32 the cyclopentene is separated from the conversion eiuent as an overhead product and is recycled to reactor 1 through line 34 and line 6. The bottom product 'from distillation zone 32 comprisingl cyclopentanol, cyclopentanone, water and polymers is passed to a second distillation zone 36 through line 33. In distillation zone 36, substantially an -azeotropic mixture of Water and cyclopentanol, and water and cyclopentanone is distilled overhead while water and polymers are removed from distillation zone 36 as a bottom product through line 31. The overhead fraction from distillation zone 36 passes through line 38 to condenser 39 and thence through line 4l to separator or accumulatorl 42. rEhe resulting condensate is separated into two liquid phases in separator 42, an upper organic phase comprising a major proportion of cyclopentanone and cyclopentanol and a lesser proportion of water and a lower aqueous phase comprising a major proportion of water with minor proportions of cyclopentanone and cyclopentanol. The aqueous phase is returned to distillation zone 36, preferably to the feed plate thereof, by means of line 43. The upper organic phase is passed from separator 42 through lnie 44 to a third distillation zone 46. A mixture of water, cyclopentanol and cyclopentanone is passed overhead from distillation zone 46 through line 41 and passed to condenser 39 and separator 42 to be separated into two liquid phases as previously described. The bottom product from distillation zone 46 comprises cyclopentanone and cyclopentanol substantially free from water. This bottom product is passed through line 48 to a fourth distillation column 49 to be separated into an overhead fraction comprising cyclopentanone which is removed through line 53 and a bottom fraction comprising cyclopentanol which is removed through line 5|. The oyclopentanol may be recycled to reactor 29 through line 52, if desired. Since the boiling point of cyclopentanone is about 130 C. and the boiling point of cyclopentanol is about 140 C. the separation of the ketone and alcohol in distillation zone 49 is effected with ease. In some instances it may be desirable to return a portion of the organic phase in separators 22 and 42 as necessary in the rectification section of the col- .umns.

When brass is used as the catalyst for the conversion of the cyclopentanol to cyclopentanone at about D-325 C. and one atmosphere pressure, the conversion is about 95 per cent, accompanied by the formation of very little water, cyclopentene, and other by-products. Although the contamination of the cyclopentanone with other compounds, such as cyclopentene, cyclopentanol, etc. is small, sufficient water may be present to warrant its removal, but in a different manner than previously described with regard to the conversion using a nickel catalyst. When a brass catalyst is used, the conversion effluent is passed from line 30 through line 56 to a first distillation zone 51 in which an overhead product comprising cyclopentanone and water along with traces of cyclopentene and a bottom product comprising cyclopentanone with traces of cyclopentanol and polymers are formed and withdrawn therefrom. The overhead product is passed from distillation zone 51 through line 59 to condenser 6I and then through line 62 to separator or accumulator 63. The bottom product comprising cyclopentanone substantially free from water is withdrawn through line 58 as a product of the process. In separator 63 an upper organic phase comprising cyclopentanone and about 13.8 volume per cent water is separated from a lower aqueous phase comprising about 29.6 volume per cent cyclopentanone. The upper` organic phase is returned to distillation zone 51 through line 64 and the aqueous phase is passed to a second distillation column 61 through line 65. Substantially an azeotropic mixture of cyclopentanone and water is withdrawn as an overhead product from distillation zone 61 through line 68 and is passed to condenser 6l and separator 63 for separation into two liquid phases as previously described. Water is withdrawn from distillation column 61 from line 59 to keep cyclopentene from building up ln the system.

In a similar manner, this invention may 'be applied to a process for the manufacture of `cy cyohexanol and cyclohexanone and to the separation of such compounds from their aqueous solutions.

The following examples are offered as exemplary of the separation described in this application, and should not be considered unnecessarily limiting to lthis invention.

Example I The separation of cyclopentanone from a dilute aqueous solution by batchwise azeotropic distillation is illustrated by the data of Tables III and IV below:

TABLE lll Charge:

60.0 cc. cyclopentanone 230 cc. distilled water Reflux ratio: 10:1 Column: Approximately 'J5 equivalent theoretical plates Vol. Vol. Total ",It Vl'oof g3g percent percent ketone Cut No. fraction phse phase zO in ketone in both c c c c c c ketone in H2O phases, phase phase c. c.

TABLE IV l l Accum Accum. Vlglllg prrceut ol. per- Overhead Bumm Out No. ketone ketone cent of temp" eter 'mm charge in the c-ha-rge o C" at lig distilled azeotrope dlstuled end of cut overhead Overhead By redistilling the combined ketone phases from cuts 1 to 4, `cyclopentanone-water azeotrope is obtained as an overhead fraction, and substantially pure cyclopentanone is recovered as a kettle residue.

Encample II The separation of cyclopentanol from a dilute aqueous solution by batchwise azeotropic distil- Qcent cyelopentanol) Column: 36 plates A y e y Vol. i Vol. Total T-otal our ivilfie rili'oor l iti rlzslt'pfcnlt slsggg leghe j V2 1n aco o 1n No' i m mit phi-15e IS'L' [alcohol in H2O phases, phases,

l c c' i L' phase phase c. c. c. c. .i t l.. 1 l 16.5 13.0 1 15.8 2 I 24.15 i 13.5` l n.0 l v13.8 12.5 I 10.0 l 2.5 i l 9.3 4` 37.0 37.0 37.0 5 20.0* 20.01 20.0

` TABLE YI 'i Acleum,

Acculn. v0 .per- A t: Bamm. vyegggggglg was? t Cut No. cent of temp. at eter. alcohol rcgv'cred alcclilol I clltd mm. H` recovered in azlotrdpe l( overhead alcohol I phase 1 .I 9. S 96, 08 T48 51 41 2 18. 0 Q6. 12 747. 5 93 75 3 22. 1 99. 40 747. 0 99 83 i.- 34.5 99.35 745.() J9 S3 5. A 42. 2 Q9. 35 74.4. 99 83 tanol under conditions such that water is formed as a by-product and forms a Water-rich soluf tion with the cyclopentanone product, the method for purifying the cyclopentanone product which comprises introducing such a liquid solution into a nrst distillation zone, removing from said rst distillation zone a bottom product comprising Water and an overhead product comprising substantially an azeotropic mixture of cyclopentanone and Water, condensing said overhead product from said rst distillation zone to form a liquid cyclopentanone-rich phase and a liquid '8 Watehrisli phase, returning said. `-waterrich nhese'to said rst distillation zone. passing said cyclopentansne-rih phase t0 a second distille- .tion Zone.. removing. an Overhead product comprising substantially an azeotropic mixture of cyclopentanone and Water from said second distillation zone and passing same to the aforesaid condensation step, and removing a bottom product. comprising cyclopentanone from said second distillation zone as a product of the process. 2. A rcontinuous process for the separation and recovery of dissolved cyclopentanone from a Water-rich solution containing the same, which comprises introducingsuch a liquid solution into a rst distillation zone, removing from said lfirst distillation zone a bottom product comprising Water and an overhead product comprising substantially an azeotropic mixture of cyclopentanone with Water,A condensing said overhead product `from said rst distillation zone to form a liquid cyclopentanone-rich phase and a liquid water-rich phase, returning said water-rich phase to said rst distillation zone, passing said cyclopentanone-rich phase to a second distillation zone,removing an overhead product c omprising substantially an azeotropic mixture of cyclopentanone and water from said second distillation zone. and passing same. to the aforesaid condensation step, and removing a bottom product comprising cyclopentanone from said second distillation zone as a product of the process.

GARDNER. C. RAY.

REFERENCES CITED The following references are of record in the ille of this patent.:

UNITED STATES PATENTS Number Name Date 1,394,232 Stevens Oct. 18, 1921 1,911,832 Lewis May 30, 1933 2,290,636. Deanesly July 21, 1942 2,368,497 Shipley et al Jan. 30, 1945 2,414,646 Hopp Jan. 21, 1947 2,417,635 Davis Mar. 18, 1947 2,439,513, Hamblet et al Apr.. 13, 1948 FOREIGN PATENTS.

Number Country Date 315,012 Germany Oct. 23, 1919 OTHER REFERENCES Randall et al., Eractionationof partiallymlscihlel liquids, 31 Industrial and Engineering Chemistry, 1181-1186 (September 1939).

Othmer, Partial pressure processes, 33 Industrial and Engineering Chemistry, 11106-1112 (September 1941). 

1. IN A PROCESS FOR THE MANUFACTURE OF CYCLOPENTANONE BY THE DEHYDROGENATION OF CYCLOPENTANOL UNDER CONDITIONS SUCH THAT WATER IS FORMED AS A BY-PRODUCT AND FORMS A WATER-RICH SOLUTION WITH THE CYCLOPENTANONE PRODUCT, THE METHOD FOR PURIFYING THE CYCLOPENTANONE PRODUCT WHICH COMPRISES INTRODUCING SUCH A LIQUID SOLUTION INTO A FIRST DISTILLATION ZONE, REMOVING FROM SAID FIRST DISTILLATION ZONE A BOTTOM PRODUCT COMPRISING WATER AND AN OVERHEAD PRODUCT COMPRISING SUBSTANTIALLY AN AZEOTROPIC MIXTURE OF CYCLOPENTANONE AND WATER, CONDENSING SAID OVERHEAD PRODUCT FROM SAID FIRST DISTILLATION ZONE TO FORM A LIQUID CYCLOPENTANONE-RICH PHASE AND A LIQUID WATER-RICH PHASE, RETURNING SAID WATER-RICH PHASE TO SAID FIRST DISTILLATION ZONE, PASSING SAID CYCLOPENTANONE-RICH PHASE TO A SECOND DISTILLATION ZONE, REMOVING AN OVERHEAD PRODUCT COMPRISING SUBSTANTIALLY AN AZEOTROPIC MIXTURE OF CYCLOPENTANONE AND WATER FROM SAID SECOND DISTILLATION ZONE AND PASSING SAME TO THE AFORESAID CONDENSATION STEP, AND REMOVING A BOTTOM PRODUCT COMPRISING CYCLOPENTANONE FROM SAID SECOND DISTILLATION ZONE AS A PRODUCT OF THE PROCESS. 